A typical ink jet printer has a pen that reciprocates over a printable surface such as a sheet of paper. The pen includes a print head having an array of numerous orifices through which droplets of ink may be expelled into the surface to generate a desired pattern. Some ink jet printers have a replaceable ink supply mounted to a stationary position on the printer, and connected to a reciprocating print head by a conduit. This permits the use of a larger ink supply, and avoids the need to replace the print head each time the supply of ink is depleted. Color ink jet printers generally have a multi-chamber cartridge, or several ink supply cartridges each containing a different color of ink.
Some existing systems provide each stationary ink supply cartridge with an on board electronics memory chip to communicate information about the contents of the cartridge. It may also be possible for such a chip to serve as a "gas gauge" that indicates or transmits to the printer the amount of ink remaining, so that the printer does not continue printing with an empty cartridge.
The on board memory in an ink cartridge may also serve to record or store other information about the ink cartridge, such as manufacture date (to ensure that excessively old ink does not damage the print head,) ink color (to prevent misinstallation,) and product identifying codes (to ensure that incompatible or inferior source ink does not enter and damage other printer parts.)
However, for very low cost applications, these advantages provided by a memory chip in each disposable cartridge may be outweighed by the cost of replacing the chip every time a cartridge is depleted. In addition, there may be other elements in a cartridge, such as structural, plumbing, and pumping components, that have useful lives that extend well beyond the time it takes to deplete the ink supply. Yet even with separate chips and ink supply elements, simply replacing or refilling the ink supply portion of an existing cartridge will not enable its operation, as the existing memory chip may continue to indicate a depleted or beyond-shelf-life cartridge, causing the printer to refuse to proceed to avoid risk of damage or faulty output. Therefore, there is a need for a low cost ink jet printing system that permits retaining non-depleted elements of an ink cartridge while restoring an ink supply, for a printer that has sensors to avoid using a depleted or dated cartridge.
The present invention overcomes or reduces the disadvantages of the prior art by providing a replaceable ink cartridge for an ink jet printer having an ink supply station with an ink receptacle and an electrical connector. The cartridge includes a chassis removable from the ink supply station, and having an ink passage and an electrical connector connectable to the printer's electrical connector. An ink reservoir is removably connected to the chassis, and has a chamber containing a supply of ink. The reservoir has an ink outlet registered with the ink passage, and the chassis has an ink level annunciator connected to the cartridge's electrical connector, for generating a signal to enable printing after the ink reservoir is depleted and replaced with a second reservoir.